DIY cable markers often lack pleasing aesthetics. Manufactured ones come in fewer choices and/or cost a lot. Perler beads come in many colors and you can get 6,000 for under $9, making them a great way to color-code your cables on the cheap.

Take a pair of scissors (or razor blade/knife) and a perler bead, then snip it down one side so it opens up. After that, just snap it on a cable and you're done. One perler bead for each end makes the cables easily identifiable by their color in just a few seconds, and for fractions of a penny.